1. Field of Invention
The present invention relates generally to apparatus for processing semiconductor wafers. More specifically, the invention relates to a lid assembly of a process chamber used for depositing material on a semiconductor wafer during a chemical vapor deposition process.
2. Description of the Background Art
Integrated circuits have evolved into complex devices that include millions of transistors, capacitors and resistors on a single chip. The evolution of chip designs continually requires faster circuitry and greater circuit density. As the demand for integrated circuits continues to rise, chip manufactures have demanded semiconductor process tooling having increased wafer throughput and greater product yield. To meet this increase in throughput, tooling is being developed to process wider diameter wafers, for example, wafers having diameters of 300 millimeters (mm).
Processing chambers generally capable of processing 300 mm diameter wafers typically have greater dimensions and internal volume than chambers designed to process smaller diameter wafers. The greater chamber dimensions correspondingly require a lid assembly disposed over the chamber to seal a vacuum environment as well as providing maintenance access.
The lids for the process chambers are connected to the chamber by a hinge and are opened during down times to perform maintenance on the process chambers. Therefore, an interface between the lid and the process chamber must include a seal, such as an o-ring, to maintain the vacuum in the process chamber and to prevent the gases used in the process from leaking into the environment. Further, when the lid is closed, it must be properly positioned on the process chamber to align the chamber components in the lid (e.g., a gas manifold in a CVD chamber) to the other process chamber components, such as the support member and a substrate positioned thereon. One observed problem is degradation in the o-ring that forms the seal. In particular, as the lid is rotated into a closed position, the lid unevenly contacts the o-ring seal beginning with the back of the chamber and then continuing to the front of the chamber until the lid is fully closed. As such, the o-ring has been subjected to pinching, nicking, and abrasion between the lid and top surface of the chamber.
One possible solution to overcome the deterioration of the seal is found in commonly owned and assigned U.S. Pat. No. 6,050,446, issued Apr. 18, 2000, to Applied Materials Inc., of Santa Clara, Calif. This prior art patent discloses a process chamber having a pivoting lid assembly that allows the lid to float above the process chamber before the lid is secured to the chamber. In particular, the lid assembly includes a lid support frame rotatably coupled to the back of the chamber by a plurality of hinges. In addition, the lid is pivotally connected to the lid support frame, preferably near the center of mass of the lid to form a pivot connection. In this manner, the lid can be positioned in parallel alignment relative to the chamber before being lowered onto the chamber and can be aligned with the chamber before being secured thereon.
Other solutions include adding a piston between the lid assembly and the body of the chamber to reduce the force of the lid as the lid closes upon the o-ring. However, there is a need in the art for an improved lid assembly that does not subject the o-ring seal to abusive forces caused by the weight and trajectory of the lid during opening and closing thereof.
The disadvantages associated with the prior art are overcome by the present invention of semiconductor substrate processing system. The semiconductor processing system generally comprises a chamber body that has a semiconductor substrate support assembly disposed in the chamber body. A lid assembly is movably coupled to the chamber body via a dual pivot hinge assembly. The hinge assembly provides two pivot points that minimize the abrasion and pinching of an o-ring disposed between the lid assembly and the chamber body upon closing of the lid assembly.
In one embodiment, a hinge assembly comprises a hinge block, a cam plate, a cam follower, and a shaft. The hinge block is coupled to the chamber body. The hinge block includes a mounting portion and a tab that projects from the mounting portion above a first surface of the chamber body. The mounting portion is disposed in a slot formed in a sidewall of the chamber body. The hinge block additionally includes a hole that generally has its centerline in the plane defined by the first surface. The hole partially houses the cam follower. The cam follower is a cylindrical member having at least a portion protruding from the hinge block. A conforming recess extending from the slot into the chamber body along the first surface accommodates the portion of the cam follower projecting from the hinge block that lies below the first surface. The tab includes an aperture. The aperture is sized to allow the shaft to move both rotationally and translationally within the aperture. The cam plate has a hole in which the shaft is partially disposed. The shaft is retained in the hole by a press fit.
The cam plate has a contoured surface that has a first portion and a second portion. The first portion is disposed at a radial distance from the aperture such that the center of rotation (i.e., a first inner pivot point) of the lid assembly has a first range of motion from an open position to a nearly closed position about the shaft and confined within the area defined by the aperture. When the lid assembly moves from the nearly closed position to a closed position to define a second range of motion (i.e., through about 5 degrees relative the first surface), the second portion of the contoured surface makes contact with the cam follower. Accordingly, the center of rotation of the lid assembly changes from the area defined by the aperture in the hinge block to the center of the cam follower (i.e., a second outer pivot point).
In a second embodiment of the first hinge assembly, the cam plate extends from the chamber body. Specifically, a hinge block is attached to the chamber body and comprises a contoured edge for interfacing with a cam follower extending from a side of a lid assembly. The contoured edge serves as a cam plate. Furthermore, the hinge block comprises an aperture for receiving a shaft coupled to the lid assembly a distance from the cam follower. The aperture is sized larger than the diameter of the shaft thereby allowing for rotational and translational motion.
When the lid assembly is in an open position, a center of rotation (i.e., a first inner pivot point) of the lid assembly has a first range of motion from an open position to a nearly closed position about the shaft and confined within the area defined by the aperture. When the lid assembly moves from the nearly closed position to a closed position to define a second range of motion (i.e., through about 5 degrees relative the first surface), the contoured edge makes contact with the cam follower. Accordingly, the center of rotation of the lid assembly changes from the area defined by the aperture to the center of the cam follower (i.e., a second outer pivot point).
In a third embodiment of the hinge assembly, a first surface of a chamber body comprises a projection that serves as a cam plate. Additionally, a hinge block is attached to the chamber body and comprises an aperture for receiving a shaft coupled to a lid assembly. The aperture is larger than the diameter of the shaft, thereby allowing for rotational and translational motion. The lid assembly further comprises a depression or contoured surface area on a lower surface area of the lid assembly. The contoured surface interfaces with the cam plate and serves as a cam follower. The cam plate is spaced at a predetermined distance from the shaft of the lid assembly.
When the lid assembly is in an open position, a center of rotation (i.e., a first inner pivot point) of the lid assembly has a first range of motion from an open position to a nearly closed position about the shaft and confined within the area defined by the aperture. When the lid assembly moves from the nearly closed position to a closed position to define a second range of motion (i.e., through about 5 degrees relative the first surface), the contoured surface area on a lower surface area of the lid assembly (i.e., cam follower) makes contact with the cam plate. Accordingly, the center of rotation of the lid assembly changes from the area defined by the aperture to the center of the cam follower (i.e., a second outer pivot point).
Coinciding with the hinge assembly of each of the embodiments is a second hinge assembly is disposed on the other side of the lid assembly allowing the rotation of the lid assembly to be defined by the first hinge assembly. The dual pivot action of the first hinge assembly allows the lid assembly to remain clear of the processing platform using the first inner pivot point defined by the aperture. The second outer pivot point defined by the cam follower seats the lid assembly with a substantially normal motion relative the o-ring, thus minimizing abrasion and xe2x80x9cpinchingxe2x80x9d of the o-ring upon closing the lid assembly.